Projectors: LCD Verses DLP (The downfall of DLP technology)
The common question customers ask when looking for a new projector for the home, office, or classroom is: would I get an LCD projector or a DLP projector? LCD, short for ‘liquid crystal device’ and DLP, short for ‘digital light processing’ are the two top projector imaging technologies. With so many company brands and different types available, it can be difficult for consumers to make a choice between both technologies. Ultimately LCD projectors offer better image quality and colour accuracy. The next paragraph tells you why DLP projectors struggle with creating an equal level of image quality.
Visualise a set of blinds in your room on your bedroom window. By pulling a rod you can have the shutters open or closed, depending on whether you want to let light in or not. Such is exactly how an LCD projector operates. Each pixel functions like an individual shutter on a set of blinds to either pass light through or to block it. DLP on the other hand is constructed of millions of microscopic mirrors or ‘pixel elements’ as professionals like to call them. Each pixel element functions to either reflect light or block it.
How the light source is processed from when the projector is turned on to when the content reaches your screen is ultimately important with regard to image quality, brightness and colour accuracy. LCD projectors direct white light from the lamp by cutting it into red, blue and green components, by three mirrors which send the coloured light to 3 separate LCD panels. The 3 LCD panels make the elements of the image by turning each pixel on and off. The pixels are then simultaneously processed in a glass prism to create the projector image. Something important to know about LCD projectors is that all three colours are delivered onto your projector screen at the same time. The way a DLP projector runs is very different and even how an image appears is not the same. With DLP, white light from the lamp is sent through a spinning colour wheel with transparent red, blue and green segments, at speeds up to 11,000 rpm/s. This method of creating an image casts a sequence of red, blue and green light. The millions of micro mirrors described above reflect the coloured light on the pixels to construct the image elements. The elements of the image are displayed in sequence on the screen, one colour at a time. The viewer’s eye will then pull together each coloured element of the image into a complete image. In LCD projectors, all colours are available all the time to deliver the top level of brightness and superb colour accuracy. In DLP, just one colour is available at any given time, resulting in lower colour brightness and accuracy. Some designers have put a white segment in the colour wheel to improve overall brightness, but this goes and degrades colour accuracy.
I hear in forums all the time that DLP offers a higher contrast ratio and ergo must be superior. For those unaware, the contrast ratio is a measure of a display system defined as the ratio of the luminance of the brightest white to that of the darkest black that the machine is able to produce. DLP projectors do have high contrast specifications as compared to a majority of LCD projectors. At a glance, this seems to be a plus, however, in truth, the true black level is determined by the ambient light in the room when the projector is used. Do not be tricked by contrast specifications on websites and in brochures.
When the content you wish to see has moving images, DLP projection technology can also have image imperfections, or ‘artifacts’. The most commonplace artifact that a DLP projector shows with moving images is colour break up. Colour break up is inherent in DLP systems because moving images change up between the time red, blue and green colours are displayed. LCD projectors do not have this characteristic because every colour is processed with the others. DLP developers have created 3DLP solutions using 3 chips to fix the colour break up issue, but the price of these projectors make them hardly practical for most businesses and consumers.
Another difference between LCD and DLP is how they match the balance for the refractive qualities of light. Remember back to high school science, and they taught you how various colours of light refract various amounts when shone through the same lens. The downside with DLP projectors is that they have the one same panel and the same lens to project Red, Blue and Green. All 3 colours are different and refract light in different ways. Generally with a DLP projector, a superfluous yellow colour will be projected above and a superfluous blue will appear below an image as simple as a single black line. While being built LCD projectors can be adjusted to minimize these effects on the projected image, because each colour is refracted on a separate LCD panels.
The isolated real benefit (excluding price) with picking a DLP projector is its smaller overall size and weight. However, this is only relevant in regard to transporting the device and must be traded off against the image advantages of LCD projectors. If the result of the picture quality is important to you, then the choice is easy. Go with an LCD projector! LCD projectors will always show bright, colourful images with fewer image mistakes. If you want to find out more about LCD technology in more detail, see this spectacular resource website: Explore 3LCD. If you have any other questions, get onto Projector Central and send me an email.
Jonathan King is the sales and marketing manager at Projector Central, Australia’s leading online provider for projectors. Brisbane-based, Projector Central has been serving Australia for 15 years. For data projectors in Brisbane and Interactive Whiteboards, contact Projector Central today.
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